This invention relates to the detection of microorganisms and more particularly to self-contained assay devices and methods of use for the detection and enumeration of microorganisms in a variety of samples such as foods, clinical specimens, and environmental samples.
Detection of microorganisms, particularly bacteria, is important in a variety of industries, including the food and beverage industry. For example, the need to screen food and water for pathogenic bacteria is crucial to ensuring consumer safety. The determination of levels of certain families of bacteria is a commonly used approach to estimating the shelf life and microbial acceptability of food products and hygienic status of the processing equipment and raw materials used in their manufacture. The diagnosis of microbial infections also relies on the detection of the causative organism (s).
There are many methods known for detecting bacteria. For example, bacteriophage, which are viruses that infect bacteria, may be employed. The presence of the bacteriophage, the infected bacteria, or the lack thereof, may be detected. These known methods suffer from various drawbacks. For example, the sample to be tested or equipment used may be contaminated during the handling of the sample. Another problem involves ease of use of the associated detection device. Still another problem encountered is the time it takes to detect a microorganism. Yet another potential problem involves containment of the components of the assay, such as for example, phage or helper bacteria, to prevent certain infection of the surrounding environment.
This invention provides devices and methods that help minimize handling concerns of assays for the detection of microorganisms, particularly bacteria. The devices and methods are relatively easy to use. In a preferred embodiment of the present invention, the methods and devices use phage amplification for relatively rapid and accurate results. Thus, using the devices and methods of the present invention, microorganism detection may be conducted in a self-contained, easy to use unit that provides relatively rapid and accurate results.
In one aspect, the invention provides a device comprising at least two chambers separated by an activatable seal wherein upon activation of the seal the two chambers are in communication. Preferably, the activation can occur by rotating (e.g., tilting) the seal, crushing the seal, or otherwise gating or opening the seal. At least one chamber of the device includes a biological assay reagent.
In another aspect, the invention provides a device comprising at least two chambers separated by an activatable seal, wherein at least one chamber includes a biological assay reagent comprising bacteriophage, an antiviral agent, or bacterial helper cells.
In another aspect, the invention provides a device comprising at least three chambers, each of which is separated by a rotatable seal, wherein a first chamber includes bacteriophage, a second chamber includes an antiviral agent, and a third chamber includes bacterial helper cells. Preferably, the second chamber is disposed between the first and third chambers and is separated into two subchambers separated from each other by a rotatable seal, wherein each subchamber includes a, different antiviral agent.
In yet another aspect, the invention provides a method for detecting the presence or absence of a microorganism, the method comprising: providing a device comprising at least two chambers separated from each other by an activatable seal, wherein at least one chamber includes a biological assay reagent; adding a sample suspected of including the microorganism to at least one of the chambers; activating the seal between one or more of the chambers to allow contact between the reagent and the sample; and detecting the presence or absence of the microorganism in the sample.
In still another aspect, the invention provides a method for detecting the presence or absence of bacteria, the method comprising: providing a device comprising at least three chambers separated from each other by activatable seals, wherein a first chamber includes bacteriophage, a second chamber includes an antiviral agent, and a third chamber includes bacterial helper cells, wherein the second chamber is disposed between the first and third chambers; adding a sample suspected of including a target bacteria to the first chamber comprising bacteriophage; allowing the bacteriophage to infect the target bacteria; activating the seal between the first and second chambers to allow contact between the antiviral agent and extracellular bacteriophage; activating the seal between the second and third chambers to allow contact between the bacterial helper cells and the infected target bacteria; incubating the bacterial helper cells and the infected bacteria; and detecting the presence or absence of the target bacteria in the sample.
FIG. 1 is a schematic of a preferred embodiment of a device of the present invention.